Дискуссионные вопросы палеогеокриологии плейстоцена и голоцена Западной Сибири в свете новых данных

Васильчук, Ю.К.; Трофимов, В.Т.

Авторы: Васильчук Ю.К., Трофимов В.Т.
Журнал: Вестник Московского университета. Серия 4: Геология
Том: 4
Номер: 3
Год издания: 1984
Издательство: Изд-во Моск. ун-та
Местоположение издательства: М.
Первая страница: 64
Последняя страница: 78
Аннотация: In our report, we are discussing four debated paleocryological problems, whose solution in light of data we have obtained takes on a new rocks at the end of the Middle Quaternary and beginning of the Late Quaternary; second, the problem of development of frozen series in the Karginskli Stage, dated 30-22 ka BP; third, the problem of the thickness of permafrost series in the northern area of Western Siberia in the Sartan Stage of the Late Quaternary; fourth, the problem of the features of development of frozen rocks during the Holocene "optimum" and of the dynamics of cryogenic processes at that time in the Arctic. Each of these problems has been discussed repeatedly in the literature, and each has - a vast bibliography. However, we will not discuss in detail the views of proponents of various viewpoints, but we will concentrate out attention on new facts and consequences deriving from them which often somewhat contradict generally accepted and customary views. We have presented new data here, connected with the use of oxygen isotope analysis. It was noted above that the age of epigenetic ice wedge in the upper part of the cross section near the village of Seyakha are dated 9.3-8.7 ka BP. The content of delta180 in them was 19.4-20.3 promille, i.e., 1-2 promille isotopically lighter than modern; expressed as temperatures this difference can be estimated at 1-3°C lower than modern (we should also mention winter and early spring paleotemperatures). It is curious that the oxygen isotope composition of ice wedge in the series of 1 terrace near the Kharasavei site, which probably formed in the "pre-optimal" period of the Holocene (according to a date 9560 ± 130 BP (IG-265D from peat horizontally bedded over the head vein), turned out to be equal to 14-15.9 parts per thousand, which is 2.5-4 promille heavier than modern ice. This suggests temperatures of the winter and early spring period of the "pre-optimal" stage by at least 3-6°C exceeding modern. Unfortunately, we still do not have other reliably dated diagrams of the oxygen isotope composition of Holocene age. However, available material lets us make two essential conclusions. First, the oxygen isotope composition differs from modern and from the Holocene by its significantly lower content of stable isotopes of 6013, which agrees well with data-from oxygen isotope determinations of ice.in Greenland and the Antarctic. Second, during the Holocene the oxygen isotope composition changed substantially; in some periods it was isotopically much lighter (at least at the beginning of the "optimum"), and in others heavier (in the "pre-optimal" stage 10-9 ka BP) than ice of modern syngenetic veins. Subsequent work will let us more exhaustively discuss this phenomenon and use it in solving problems of paleocryology.
Добавил в систему: Васильчук Юрий Кириллович

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